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Far Field Equation:
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The Far Field Distance is the distance from an antenna beyond which the radiation pattern is well-established and the electromagnetic waves propagate as plane waves. It is a critical parameter in antenna design and electromagnetic compatibility testing.
The calculator uses the Far Field equation:
Where:
Explanation: This equation determines the minimum distance at which the antenna's radiation characteristics become stable and predictable.
Details: Accurate far field distance calculation is essential for proper antenna testing, measurement setup, and ensuring valid radiation pattern measurements in anechoic chambers and open area test sites.
Tips: Enter the antenna's largest dimension (D) in meters and the wavelength (λ) in meters. Both values must be positive numbers greater than zero.
Q1: Why is the far field distance important in antenna measurements?
A: The far field distance ensures that measurements are taken at a distance where the antenna's radiation pattern is fully developed and stable, providing accurate characterization of its performance.
Q2: What factors affect the far field distance?
A: The far field distance primarily depends on the antenna size (D) and the operating wavelength (λ). Larger antennas and higher frequencies (shorter wavelengths) result in longer far field distances.
Q3: How is wavelength related to frequency?
A: Wavelength (λ) = speed of light (c) / frequency (f). For practical calculations, λ = 3×10⁸ / f (where f is in Hz and λ is in meters).
Q4: Are there different criteria for far field distance?
A: Yes, while 2D²/λ is a common criterion, some applications use more conservative distances such as 3D²/λ or 10D²/λ for higher accuracy requirements.
Q5: Can this calculator be used for any antenna type?
A: This formula is generally applicable to most antenna types, but specialized antennas with unusual radiation characteristics may require additional considerations.